Different operators across the world have their own fibers and network equipment. Inside their subnets, the operators are solely responsible for management, maintenance and fault location of the network equipment. Moreover, the network equipment between different operators needs to connect into a greater network to serve users. That is, an end-to-end user service may be transferred through subnets of different operators. In this case, a mechanism is required to identify the quality of subnets of each specific operator.
In order to evaluate the network quality of different operators, the concept of TCM is put forward. The TCM can monitor subnets and monitor the quality of a section of trail that transfers an end-to-end service.
The Optical Data Unit (ODU) layer of an Optical Transfer Network (OTN) defines six levels of TCM overheads (OH). Each TCM overhead includes information such as Trail Tracking Identifier (TTI), Bit Interleaving Parity-8 (BIP-8), Backward Defect Indication (BDI), Backward Error Indication (BEI), State field (STAT), and Backward Incoming Azimuth Error (BIAE). The TCM can monitor continuity, connectivity, and signal quality.
According to the G.798 recommendations, in allocating six TCM levels for an end-to-end service, networks of various topologies provide an interface for the user to decide allocation and use of TCM levels.
To activate the TCM function, the user needs to set the function for each node that uses the TCM function set the TCM level and mode. The services in two directions can be set separately. For each node, a mode can be set for a TCM level (level 1 to level 6) in the source direction (transmitting direction), and a mode can be set for a TCM level in the sink direction (receiving direction). Namely, for a node, for handling a unidirectional service, the mode in the receiving direction and the mode in the transmitting direction are configurable.
The modes for the transmitting direction include an OPERATIONAL mode and a TRANSPARENT mode.
If a TCM level is set to the OPERATIONAL mode, the TCM of this level will undergo regeneration processing, for example, inserting BIP8, BEI, BIAE, BDI, TTI, and so on.
If a TCM level is set to the TRANSPARENT mode, the TCM of this level needs no processing.
The modes for the receiving direction include an OPERATIONAL mode, a TRANSPARENT mode and a MONITOR mode.
If a TCM level is set to the OPERATIONAL mode, the TCM of this level will be monitored, for example, monitoring the overhead of BIP8, BEI, BIAE, BDI, and TTI, and generating the corresponding defect; and will be undergo subsequent processing, for example, generating Alarm Indication Signal (AIS), and Trail Signal Failure (TSF).
If a TCM level is set to the MONITOR mode, the TCM of this level will be monitored, for example, monitoring the overhead of BIP8, BEI, BIAE, BDI, and TTI, and generating the corresponding defect; but without undergoing subsequent processing such as AIS and TSF.
If a TCM level is set to the TRANSPARENT mode, the TCM of this level needs no processing.
For bidirectional services, each direction is set separately.
Moreover, a contract may be signed between different operators to specify the TCM allocation.
However, the drawbacks of the prior art are: The TCM has to be allocated by the user, without providing automatic allocation. Moreover, the information such as configuration modes available to the user is not direct-viewable enough, and is perplexing to ordinary users.
In addition, one or more TCM levels are allocated to each domain fixedly in the prior art, which makes the TCM levels not enough for allocation when there are more than six domains. In this case, if multiple domains use one TCM level, another domain may attempt to use a TCM level seized by an existing domain, which makes the allocation impossible. However, another TCM level may be idle at the moment. Even if the inclusive relation of domains is considered in the fixed allocation, for example, if the prior art stipulates that a domain with an inclusive relation must not use the same TCM level fixedly, it is not necessarily appropriate.
As shown in FIG. 7, there are 16 nodes ranging from A to P in the networking diagram.
The bulleted items in FIG. 7 represent the network scope of a certain domain (for example, operator).
Domain 1: B, C, F, G
Domain 2: B, C, D, F, G, H, J, K, L
Domain 2 includes domain 1. It may be inappropriate to forbid domain 2 and domain 1 to use the same TCM level, because they should use the same TCM level properly in some circumstances. Such forbidding may be unreasonable.
Suppose that an ODU1 service is routed from node A through B, C, D, H, G, F, E, I, J, K, L to node P. A TCM needs to be allocated for the BCDHGF scope and the JKL scope of the service. A TCM needs to be allocated for the BC scope and the GF scope of domain 1. The BC scope and the GF scope of domain 1 cannot share a TCM level with the BCDHGF scope of domain 2, but can share a TCM level with the JKL scope of domain 2. Namely, the TCM allocation should consider not only the relation between domains, but also the trail of specific services and the topology of domains.
In a word, if the TDM level is allocated fixedly, it is possible that an expected TCM level is seized but other TCM levels are idle. Namely, the beforehand fixed allocation is unable to suit the complex network topology and service trails.